title: Extramedullary IgM plasmacytoma presenting in skin.
abstract: An IgM-secreting extramedullary plasmacytoma with macroglobulinemia presented itself in the skin. Reactions of the plasmacytoid cells in dermal nodules to erythrocyte-antibody-complement complexes suggested that the neoplastic cells differentiated in situ. Large numbers of plasmacytoid neoplastic cells co-mingled with alpha naphthyl acetate esterase-positive histiocytes in a random and "territorial" distribution, which suggested a functional relationship between them. The subject of extramedullary cutaneous plasmacytoma is reviewed and discussed.
mesh_terms: D000912:Antibodies, Neoplasm; D006801:Humans; D007075:Immunoglobulin M; D008297:Male; D008875:Middle Aged; D010954:Plasmacytoma / Q000276:immunology / Q000473:pathology*; D012186:Retroperitoneal Neoplasms / Q000276:immunology / Q000473:pathology; D012867:Skin / Q000473:pathology; D012878:Skin Neoplasms / Q000276:immunology / Q000473:pathology*; D008258:Waldenstrom Macroglobulinemia / Q000473:pathology
chemical_list: D000912:Antibodies, Neoplasm; D007075:Immunoglobulin M